1. United States Department of Agriculture, Agricultural Research Service, Infectious Bacterial Disease Research Unit, National Animal Disease Center , Ames, Iowa, USA
2. Department of Veterinary Diagnostic and Production Animal Medicine, College of Veterinary Medicine, Iowa State University, Ames, Iowa, USA
3. Department of Veterinary Microbiology and Preventive Medicine, College of Veterinary Medicine, Iowa State University, Ames, Iowa, USA
4. Department of Agricultural and Environmental Sciences, College of Agriculture, Tennessee State University, Nashville, Tennessee, USA
5. United States Department of Agriculture, Agricultural Research Service, Virus and Prion Research Unit, National Animal Disease Center, Ames, Iowa, USA
6. Department of Diagnostic Medicine/Pathobiology, College of Veterinary Medicine, Kansas State University, Manhattan, Kansas, USA